The present invention relates generally to the conveyor art, and, more particularly, to a conveyor section for diverting articles using a belt diverter.
U.S. Pat. No. 4,050,573 discloses two receiving conveyors which extend at opposite sides of the longitudinal axis of the intake conveyor.
U.S. Pat. No. 4,598,814 discloses articles being transported in a horizontal plane and having diverters.
U.S. Pat. No. 4,733,768 discloses a diverting device for diverting an individual cookie from one conveyor to another location.
U.S. Pat. No. 5,188,210 discloses a conveyor having vertical side conveyors and has a diverter, the flat mail being disposed in a vertical plane.
There is a problem in the prior art in that the flat paper mail is to maintain movement at a constant speed over a pocket diverter in a mail sorter which has the transport in the horizontal plane. Particularly when dealing with xe2x80x9cflatxe2x80x9d mail, which will inherently require a longer diverter, the friction between the mail piece and the diverter will slow the mail piece down causing subsequent pieces to catch up. This changes the spacing of the mail making tracking impossible and potentially causing jams. Also, there is a large variation of mail pieces and also such a variation of frictional forces. In the prior art it is difficult if not impossible to maintaing the flat articles at a constant velocity. This makes tracking difficult if not impossible. The diverter need to be larger or longer due to the flat mail specifications. Most of the traditional diverters are solid and of one piece. Also, the trailing mail pieces can catch up to the leading mail pieces thereby causing jams.
Having a movable section of a horizontal transport divert down is cumbersome due to the mass of the transport that is being moved.
It is an object of the present invention to provide a simple, inexpensive device which will divert selected flat articles.
It is another object of the present invention to provide such a device which does this less expensively and more quickly than prior art devices.
A further object of the present invention is to provide such a device with a robust mechanical design and robust control arrangement.
It is a still further object of the present invention to provide such a device in which the drive for the diverted flat articles is arranged so that the driving of the belts assists the movement of the diverter.
It is yet another object of the present invention to provide a flat mail diverter in which the horizontal transport is not moved when the mail is diverted.
An object of the invention is also to provide a diverter in which diverter gates are used to divert the flat mail and the transport remains horizontal.
These and other objects are accomplished by a system which has diverter gates with moving belts and the diverter becomes an integral part of transport. The diverter serves two functions, to divert mail and transport mail along the transport path. Narrow belts are used which are staggered with fixed transport. Idler rollers of a fixed transport are used to drive the diverter belts. Small rollers are provided at the leading edges of the diverters and the belts move over there rollers. The parts are of molded structural foam although other materials are possible. Also, the shaft and wear plates under belt path are molded in.
This construction provides the following advantages and features. No additional drive shaft or drive roller is required. The pretension in the belts helps to lift the diverter due to there being different pivot centers for the drive rollers and the diverter pivot. There are very few parts, only three for the subassembly. They are: the diverter, the rollers, and the belts. Also, the device is lightweight, weighing only 60 oz and is rapidly actuated, requiring an opening time of only 80-90 milli-seconds.
There is minimal diverting force required of approx. 13 lbs, and xc2xexe2x80x3 bore xc3x97 xc2xexe2x80x3 stroke. It is inexpensive, since the diverter can be made for $32, the rollers for $10-15, and the belts for $1.20.
The present invention provides a solution which is better than the prior art because moving a section of transport requires a lot of energy or force due to the mass involved. The present invention does effectively makes the diverter an integral part of the transport but in a manner that keeps the mass and diverter energy to a minimum. This is done by using a structural foam for the material and the natural pretension in the transport belts to help lift the diverter.
The present invention solves the problem by incorporating rotating belts into the diverter of a mail sorter which utilizes a horizontal paper transport. Eliminating the problem of changes in speed and gap of the mail pieces.
The same rotating belts that are part of the fixed (stationary) transport are used in the diverter. This is accomplished by placing small transport rollers into the leading edge of each diverter gate and then installing transport belts around them and back around the stationary transport idler roller. Wrapping the belts around this idler roller instead of placing additional rollers at the trailing edge of the diverter accomplishes several benefits. Reduces the weight of the diverter, requires no additional drive pulley (driven from the stationary transport section) and allows the pretension of the belts to help lift the diverter.
The diverter of the present invention is part of a flat mail (USPS specifications.) transport which is conveying the mail in a horizontal plane. Diverters are required in order to sort the mail into xe2x80x9cpocketsxe2x80x9d located below the transport. Rotating belts are added to the diverter gate in order to keep the mail moving at a constant velocity. The rotating belts, as part of the diverter gate, is the key feature of the design. Without the rotating belts the frictional forces acting on the mail as it goes over the diverter gate would slow the mail pieces down causing the trailing mail pieces to catch up the previous piece. The situation is aggravated by the large variation in the mail specifications (size, weight, material, and the like).
The manner in which the diverter belts are driven is another unique feature of the design. By wrapping the belts around the idler roller (adjacent to the trailing edge of the diverter gate) of the fixed portion of the transport no additional drive mechanism is required. The main advantage to this design is that no additional weight, other than the belts, has been added to the diverter. Weight is the key factor in getting the opening/closing time required.
Another design advantage is obtained as a secondary benefit from the xe2x80x9cbelt drive methodxe2x80x9d described above. Due to the different pivot centers of the diverter gate and the belts around the fixed transport idler roller the belts themselves actually help lift the diverter gate. This additional lift force is proportional to the belt pretension.
Design simplicity is a further benefit to the design. In one embodiment there are only three parts (and/or sub-assemblies): the diverter gate (molded assembly); belt rollers (five); and the belts (five).
Other objects, features and advantages will be apparent from the following detailed description of preferred embodiments taken in conjunction with the accompanying drawings in which: